I have a Modicon Quantum installed in a large mineral seperation plant, the programing software is concept v2.6. The plant has about 2000 I/O points of which there is about a 50/50 spilt between analog and digital. These are currently all on the modicon 800 series racks as the quantum replaced the 984B. The plant is about 500 m from the plc. The racks are localized in the plant.

We are looking at installing about 100 new analog points and am lookinf at a bus as apposed to installing new racks.
In time we would like to put the existing "multi-parameter, down-loadable, high-level" instruments onto the network as aposed to just getting a 4-20ma signal.
Please give me your informed opinion as to which bus systum would be better suited to my application as discribed.

Hello Murray;
We have worked with Quantum CPUs last year, on a large (13000 + I/O points) distributed control system upgrade for a loading dock. In order to be able to maintain the original TI500 racks, we installed Profibus masters in all the central racks (with Profibus RBCs replacing the TI CPUs). The I/O setup went like a charm, and mapping the Profibus I/O to the Modicon addresses was easy. We also inserted ET-200M racks for newer I/O points over Profibus (both discrete and analog), and used Profibus-PA links to connect temperature, pressure and weight transducers (Siemens and Endress & Hauser)over an intelligent bus. (Using PA and PDM software required a bit more of a learning curve, but the results were very worth while).
All in all, I can't help but recommend Profibus as a distributed system for Modicon PLCs.